Movement dampers are used in a wide variety of devices to control the movement of device components. In some situations, dampers are used to control movements of components that would otherwise move more suddenly and forcefully than desired. The damper may control movement caused by gravitational forces or movement induced by springs or other actuators. Doors, drawers and pullouts in furniture are some examples of known applications for dampers. In automobiles, dampers are known for use on, for example, glove box doors, console covers, sunglass bins, retractable cup holders and other storage bins or storage areas. Many other devices also use dampers.
Viscous dampers are known. In a viscous damper a rotor is rotatable within a housing that contains a viscous damping fluid. Internal structures of the rotor and/or housing establish ports for relative movement of the damping fluid and rotor, thereby providing a desired degree of resistance or “damping”.
Both one-way and two-way dampers are known. As the names imply, a one-way damper controls movement in only one direction while applying minimal resistance to movement in the opposite direction, and a two-way damper provides resistance or control of movement in both directions. To provide one-way damping, it is known to have driving structure between the damper and the component controlled that engages for movement in one direction and disengages for movement in the other direction. The engagement and disengagement can be problematic if not effected completely, and operation is compromised if not firmly engaged and/or noisy if not completely disengaged and separated.
It is known to use automatically retracting straps to control or direct crowd movement. For example, in public facilities, it is known to provide a plurality of self-standing posts or pedestals with reel assemblies at the tops thereof, each having a length of nylon or other webbing material wound therein. Each post further includes one or more slot for engaging an end of a strap from an adjacent post. The stands are moved and arranged easily, with the straps connected therebetween to designate paths for crowd movement, to block areas people are to be restricted from and to otherwise define pedestrian traffic patterns when necessary. The web or strap is extendable outwardly from the reel, often tightening a spring or other retraction device in the process so that when the web is released it automatically retracts, rewinding on the reel. To ensure efficient and complete wind up, and to hold the web securely in the wound up state, the automatic drive features are known to be both strong and rapid. However, the rapid roll-up of the web having a hardened plastic fixture at the distal end thereof for engaging an adjacent post can cause random whipping and uncontrolled movement as the extended web length rapid shortens. In large crowds it sometimes happens that a post is inadvertently tipped over causing attached straps to disengage within a crowded area. Individuals leaning on a post or strap, individuals manipulating or moving the components and other random acts can cause an unintended disengagement of strap ends from adjacent posts, and the rapid, random wind-up that sometimes occurs.
It is desirable to provide a crowd control device with a more effective damper, and a damper that engages and disengages effectively for use in the crowd control device and other structures.